U.S. armored vehicles designed to push explosions away

KABUL — The U.S. military is reluctant to discuss the specifications of the Mine Resistant Ambush Protected armored vehicle and its all-terrain variant, and how they protect their crews from homemade bombs. A cursory glance at the vehicles offers some clues, however.

Both vehicles' cabins are so high off the ground that their drivers and passengers need to climb a couple of steps to get into them. Inside is a fire extinguishing system that activates automatically.

Perhaps most importantly, the MRAP and M-ATV hulls form a "V" to push an explosion away from the crew inside.

The insurgents, however, aren't standing still, either. In the last year, their improvised explosive devices have grown larger, heavier and more powerful, and in some cases several of them are "daisy-chained" together. The majority of IEDs in 2008 weighed less than 25 pounds each; now the vast majority of them weigh more than 25 pounds, and some of them well more than that.

"We've had charging weights of 2,000 pounds that have destroyed our MRAPs," said a senior International Security Assistance Force intelligence official, speaking on the condition of anonymity because intelligence is classified.

Insurgents in recent years also have perfected the design of IEDs, making the explosives out of ammonium nitrate fertilizer — which Timothy McVeigh used in the 1995 Oklahoma City bombing — instead of the leftover military explosives they were using before 2007.